If you observe Mars from one opposition to another, you can see the Martian weather and seasons change. Mars has a tilt similar to Earth's and experiences four seasons, each lasting about twice as long as ours because Mars's orbit is that much larger.
Martian seasons do not correspond exactly with Earth's, because Mars's polar axis points in the direction of the star Deneb, whereas Earth's points to Polaris. A handy rule of thumb to remember is that the season on Mars at each opposition is one season in advance of Earth's at that time.
For Mars's northern hemisphere, spring and summer generally feature a clear atmosphere with little dust in the air. Whitish clouds, however, can appear near the sunrise line and over high elevations. Frost deposits turn the large impact basins of Argyre, Hellas, and Elysium into bright patches. You will find that filters excel at revealing details such as these,especially when alternated with unfiltered views.
The northern polar cap vanishes under a hood of cloud during its fall and winter. The plummeting temperatures renew the ice cap by condensing carbon dioxide from the atmosphere. The carbondioxide ice comes and goes with the seasons, but a permanent water-ice cap in the north remains intact throughout the summer.
Because the southern-hemisphere summer occurs at perihelion—when Mars lies closest to the Sun— sunlight is 44 percent stronger at this time. This makes southern summers hotter, and winters colder, than northern ones.
The southern polar cap is mostly carbondioxide ice. During summer, it shrinks to a tiny remnant (with a core of water ice), but does not vanish completely. About every 17 years, when opposition coincides with perihelion, the southern polar cap is tilted toward Earth, showing clearly as it shrinks under the Sun's strong rays.